Course Home | Syllabus | Assignments | Schedule | Downloads | Submissions | [print]

IT 3100: Systems Design and Administration I

Relaying Email (Satellite Systems)

Due according to the class schedule.


It is important for outgoing email messages to be sent from most systems on a LAN through the centralized MTA. At this time in the semester, you should have several other systems on your LAN. (DNS, web, resources, file systems, etc.)

In this assignment, you will configure the MTA to relay email for these other systems, and to receive messages that were originally addressed for those systems.

You will also configure the systems to send their email messages through the MTA, and not to receive any email messages.

Throughout the semester these systems must continue to forward email through your MTA.

Configure LAN systems to relay all email through the MTA system

On each of the existing systems (except the MTA), install and configure the exim4 software to use your MTA as a smarthost.

On each of the existing systems, install the MUA mailx via the package mailutils. Also install python-minimal.

These systems should be configured not to receive email.

Configure the MTA to receive incoming messages for the satellite systems

The server should accept email for users at any of the hosts in your domain. (e.g.

The DNS should be configured to direct any SMTP messages for any of the hosts in your domain to your MTA.

Configure the MTA to relay outgoing messages for the satellite systems

The email server should relay email for any user at any satellite system in your network. (e.g. Email from should be relayed to its destination.)

User account creation

Create a new user account on the satellite systems. This should have the same username and password as the account created on the MTA system in the previous SMTP assignment.


Verify that your system is sending and receiving email messages correctly. You’ll want to consider the source and destination of the messages.

There are several locations to send from, and several locations to send to. This makes many possible combinations. To be sure your system is working correctly, check them all.

Use the log files to look for potential errors.

Submission File Format

The submission file is a UNIX text file, and must have this format, exactly!

The file must be named smtp_info.txt.

mta:    ip_address_of_MTA
user:   user_name_created_for_passoff
pass:   password_for_user
host:   name.of.mta.machine
domain: name.of.domain
hosts:  ip_address_of_satellite_host1, ip_address_of_satellite_host2, ...

For example, my file might look like this:

user:   bbonzai
pass:   $&^bbi13

Submission and Passoff

Last Updated 08/07/2020